Control for fuel burners



NOV. 27, 1934. W, l;l STARK 1,982,031

CONTROL FOR FUEL BURNERS4 `Filed May 27, 1953 /A/VE/v'ro'e.- Maar .574er 4free/vers Patented Nov. 27, 1934 PATENT OFFICE CONTROL FOR FUEL BURNERS Willet E. Stark, East Cleveland, Ohio, assignor, by

mesne assignments, to The Bryant Heater Company, Cleveland, Ohio, a corporation of Ohio Application May 27, 1933, Serial No. 673,261

20 Claims.

This invention relates to gas burning heating apparatus of -the types known as boilers and air furnaces, and has for its primary object to provide an improved control therefor, preferably automatically operated, which results in a more efficient operation and consequent increased econ'- omy.

In boiler and furnace installations of this type, it is customary to provide directly above the boiler or furnace a draft hood and to connect the latter with the chimney by means of a flue pipe.

The draft hood has two primary purposes, one of which is to deect any down drafts that might come down the chimney, allowing them to ow out through the relief opening in the draft hood and thus prevent interference with the combustion in the combustion chamber. The other purpose is to admit air from the boiler or furnace room into the chimney, breaking the effect of the chimney draft on the boiler or furnace itself, and keeping constant the draft actually exerted on the boiler or furnace, thereby neutralizing the effect of variable chimney draft. In this latter condition, air from the boiler or furnace room is constantly drawn up the chimney during periods of operation. This air that enters the draft hood and goes on up the chimney must come from the boiler or furnace room, and the air to replace that drawn from the boiler or furnace room necessarily comes from out-of-doors, and before it enters the opening in the draft hood, it is heated from the out-of-door temperature to the boiler or furnace room temperature by heat coming from within the room itself. If this heat were not withdrawn from the boiler or furnace room, it would be usefully applied in heating the structure in which the boiler or furnace is installed. For example, it would keep the basement ceiling and, therefore, the floor of the lower story vofla house Warm. This loss goes on, not only when the boiler or furnace is in operation, but also when it is turned off as by automatic control. Thus, heat is being abstracted from the house constantly unless measures are taken to prevent it.

It is therefore a .further object of the present invention to provide means whereby the air drawn from the boiler or furnace room into the ue pipe through the draft hood is controlled so that only the necessary amount of air is withdrawn during the operation of the boiler.. or furnace for utmost efliciency in so far as combustion is concerned and practically no air is withdrawn from the boiler or furnace room when the boiler or furnace is not in operation, thus conserving the heat and more efficiently heating the house.

Another object of the invention is to provide means for controlling the air passing through the draft hood coincidentally with the control of the gas flow to the burners, the said means preferably operating in a manner such that the iiow of air from the boiler or furnace room through the draft hood is prevented upon the closure of the main gas valve and is permitted upon the opening of the valve.

A further object is to provide a damper or equivalent device for the control of the air passing through the hood and to provide for the actuation of this device a diaphragm or other pressure responsive means which is actuated when the main gas valve, which isl preferably of the diaphragm type, is closed'or opened, and to provide a control for the pressure responsive means and for the diaphragm such that they are both actuated quickly notwithstanding the fact that there may be used in the control mechanism a thermally actuated device or a steam pressure responsive device operating on a gradually-acting control valve.

A further object of the invention is to provide for the control of the passage of air from the 30 furnace or boiler room lthrough the draft hood a damper or equivalent device which is actuated by gas pressure with a quick action simultaneous-` ly with lthe operation of the main gas valve and simultaneously therewith controlled by any of the instrumentalities which are customarily utilized to bring about the closure and opening of the main gas valve, such as a thermostatic device actuated by room temperature, or a water temperature thermostat, or a device controlled by steam pressure in the boiler which is equipped with the control mechanism constituting the subject matter of the present invention.

A still further object is to provide for the damper or equivalent control device an operating mechanism which functions wholly independently of variations in pressure on the outlet side of the main gas valve, such as might be produced by utilizing a control mechanism for the main gas valve s uch that the valve is adapted toassume intermediate positions between the closed and wide open positions.

With the objects above indicated and other objects hereinafter explained in view, the invention consists in the construction and combination of elements hereinafter described and claimed.

Referring to the drawing:

Figure 1 is a diagrammatic illustration of a control system embodying the present invention;

Fig. 2 is a cross-sectional view taken on line 1'10 2-2 of Fig. 1 and showing in detail the construction of the flue pipe damper; and

Fig. -3 is a fragmentary side elevational view of a boiler or furnace showing the manner in which the invention is incorporated therein.

In the drawing I have illustrated more or less diagrammatically a control system which may be adapted to either a boiler or an air furnace, as may be desired, for controlling the flow of fuel, which in this instance is gas, to the main burners for heating the sections of the boiler or furnace. In conjunction with the operation of the fuel control, a damper in the flue pipe is caused to be moved to open or closed position, depending upon whether the main gas valve is being opened or closed, in a manner which will be hereinafter more fully described.,

In Fig. 3 I have illustrated a general arrangement, including a boiler or air furnace 10 having adraft hood 11 mounted thereon in the customary manner and to which one end of a flue f interfere with proper combustion.

pipe 12 is connected, while the opposite end of the flue pipe is adapted to be connected to a chimney in the usual manner. The draft hood ll, as already stated, has two primary functions, one being to deflect any down drafts that might come down the chimney, allowing them to flow out through the relief opening 13 in the draft hood 11 and thus prevent their admission to the combustion chamber which would otherwise The other function of the draft hood is to admit air from the boiler`4 room through the relief opening .13 in the draft hood, as indicated by the arrows, into the flue pipe 12 and subsequently into the chimney, thereby tending to break the effect of chimney draft on the boiler itself.

In the present types of installations, air from the boiler or furnace room is being continuously withdrawn through the draft hood 11, both during the operation of the boiler and also when the -boiler is not in operation.v While-the boiler is in operation, it naturally has a tendency to heat the boiler room and consequently the air whichV .is drawn therefrom through the draft hood contains considerable heat units. Fresh air from out-of-doors must replace the air which has been withdrawn from the boiler room, and, as itis of a substantially lower temperature, the heat from the boiler'room is required to raise the temperature of the incoming air. There is, therefore, a considerable quantity of heat units being abstracted from'the heating system, resulting in ineflicient operation.

To prevent entirely the loss of` heat from the boiler or furnace room during the time that the boiler is not in operation, a damper 15 is provided in the flue pipe 12 between the outlet of the draft hood 11 and the chimney. This damper 15 is adapted to be closed when the boiler is not in operation, but to be open when the boiler is in operation. To reduce to the lowest possible figure, consistent with safe operation, the loss of heat from the boiler room due to air being drawn through the draft hood and into the chimney while the boiler is in operation, the damper 15 is made adjustable so that it can be adjusted to cause the chimney to exert some desired amount of draft tension, for example, two-hundredths of an inch, on the outlet side of the draft hood 11. '11., adjustment of the open position can also be/ determined with the aid of a flue gas analysis apparatus. K

Referring now to Fig. 1 which illustrates the preferred system for controlling the operation of the damper 15 in the flue pipe 12, there is provided a main fuel supply line 16 which may ube connected at one end to any suitable source of fuel supply, such, for example,'as gas. The outlet side of the fuel line-16 is connected to a main diaphragm valve l7. An outlet pipe 18 is connected with the outlet side of the main diaphragm valve 17 which in turn is connected with a burner 19 disposed beneath the sectional heating units arranged Within the boiler 10. Only one burner 19 is herein illustrated, but it should be understood that any number of burners may be employed, depending upon the required boiler capacity. A pilot burner 20 is disposed adjacent the burner 19 and is connected by means of a pipe line 2l with the' main fuel supply line 16, so that fuel is constantly supplied to the pilot burner.

The main diaphragm valve 17 is provided with a valve seat 22 with which a valve disk 23 is adapted to engage 4to control the flow of fuel through the main diaphragm valve 17 to thereby control the operation of the burner 19. The valve disk 23 is secured to the under side of a diaphragm 24 having its peripheral edge secured in the usual manner to the housing of the main diaphragm valve. A fuel line 25 is connected with the main fuel supplyline 16 and with the main diaphragm valve 17 above the diaphragm 24, so as to permit fuel to pass from the main supply line 16 into engagement with the upper side of the diaphragm 24. A normally closed valve 26 is disposed in the fuel line 25 and, in the present instance, is actuatled by means of a solenoid controlled in a manner to be later described, through the medium of a thermostat located so as to control the temperature of the dwelling or building in which the boiler or furnace installation is made. When this valve 26 is in closed position, it prevents the flow of fuel to the upper side of the diaphragm 24 and, as a result of the preponderance of pressure of the fuel upon the lower side of the diaphragm 24, the valve disk 23 is moved from its seat 22 and fuel is permitted to pass to the burner 19. However, when the valve 26 is moved to open position, fuel is permitted to pass through the fuel line 25 into engagement with the upper side of the diaphragm 24, with the result that there is a balancing of pressures which causes the valve disk 23 to move into engagement with the valve seat 22 by the action of gravity and shuts off the flow of fuel to the burner 19. To relieve the pressure of the fuel in the fuel line 25 when the valve 26 is closed, an escapement burner 27 is provided and is connected with the fuel line 25 by a fuel line 28 which has a restricted orifice 29 provided therein.

A diaphragm valve 30 is provided for also controlling the operation of the main diaphragm valve 17 so as to effect a quick opening and closing of the diaphragm valve 17. This diaphragm valve 30 has a diaphragm 31 which is secured at its peripheral edge in the housing of the valve. A fuel line 32 has one end connected preferably to the fuel line 25, which is in communication with the upper side of the diaphragm 24 of the main diaphragm valve 17. This diaphragm valve 30 has a valve seat 34 with which a valve disk 35 normally engages so as to prevent the flow of fuel through the valve 30, the valve disk 35 being connected to the under side of the diaphragm 3l in any suitable manner. A fuel line 36 connects the fuel line 32 with the upper side or chamber of the diaphragm valve30, and there is provided in the fuel line 26 a restricted orifice 37 which may be removed for cleaning or other purpose by the removal of a screw-threaded plug 3'8 provided in a T-connection 39 in the fuel line.

The operation of this diaphragm valve -30 is preferably controlled by means of a thermally actuated valve 40 responsive to temperature conditions of the water in the boiler being heated, although it may be controlled by a valve responsive to some other condition of the boiler or furnace, such as steam pressure. 'I'his valve 40 is provided with a housing 41 having a dividing partition 42 formed integral therewith, the partition having a transverse opening therein and a valve seat 43 which is normally engaged by a valve disk 44. A coil spring 45 is positioned axially of the valve disk 44 within the housing 41 and has one end abutting the inner surface of the housing while the opposite end is in engagement with the adjacent surface of the disk 44, this spring 45 tending to urge the valve disk 44 out of engagement with the valve seat 43. A fuel line 46 has one end connected to the fuel line 36 and its opposite end connected to the housing 41 of valve 4Q and communicates through a passageway 47 with the interior of the housing 4l on that side of the valve disk 44 on which is located the spring 45. A fuel line 48 has one end connected with the housing 41 and is in communication with the latter on the other side of the valve disk 44 by means of a passageway 49, while the opposite end of the fuel line 48 is connected with the escapement burner 27 at a point located above the restricted orifice The thermally responsive device may be inserted in the ow line of one of the boiler sections 50 which is being heated by the burner 19 and, while it can be constructed differently than here shown, in this instance it includes a tube 5l closed at one end and open at the other, and made of a metal having a high coefficient of expansion, such as copper. The open end of the tube is exteriorly screw-threaded and is mounted within a screw-threaded opening in a plug 52 which, in turn, is secured to the boiler 10 in any suitable manner. The plug 52 has an axial opening therethrough through which vextends a screwthreaded rod 53., The inner end of the rod 53 is secured to one e'nd of a rod 54 which is disposed within the tube 51 and is made of a metal having a low coefficient of thermal expansion, such as nickel steel. A pointer 55 is mounted for adjustment upon the free end of the rod 53 and adjusts the rod 54 with respect to the tube 51 so as to control the operation of the valve 40. A rod 56 is slidably mounted in the housing 41 of valve 40 and has one end in engagement with the valve disk 44 and the opposite end in engagement with the free end of the rod 53.

The damper 15 is pivotally mounted in a ring 57, as more clearly shown in Fig. 2, this ring 57 being mounted between two closely adjacent sections of the flue pipe 12 (note Fig. 1). A shaft 58 vis secured to the damper plate 15 and has its ends journaled in recesses provided in the inner ends of screw-threaded bolts 59. These bolts are adjustably mounted in extensions 60 formed integral with diametrically opposite portions of the ring 57 and may be secured in proper position by means of lock nuts 61. A crank 62 has one end connected by means of a setscrew 63 to the shaft 58 near one end thereof so that the angular position of the crank 62 may be adjusted on the shaft 58, while the opposite end of the crank is pivotally connected at 64 to the upper forked end of a link 65. The lower end of the link 65 is pivotally connected at 66 to the forked upper end of a rod 67.

The damper 15 is preferably operated by means of a pressure responsive device which, in the present instance, comprises a housing 68 having a diaphragm 69 disposed therein, the peripheral edge of which is secured to the housing in any suitable manner. The upper portion of the housing 68 is provided with an opening 70 in which the rod 67 is adapted to reciprocate, this rod being connected to the center of the diaphragm 69 in any suitable manner so as to be moved therewith. The rod 67 is screw-threaded at its upper portion and has mounted thereon a nut 71 which is adapted to engage the upper surface of the housing 68 and limits the downward movement of the rod 67. By adjusting this nut 71 upon the rod 67, the angularity of the damper 15 within the flue pipe 12 may be adjusted so as to control the amount of draft tension exerted by the chimney.

A relief opening 72 is provided in the upper portion of the housing 68 above the diaphragm 69 so that the air which is present above the diaphragm 69 may be readily exhausted to atmosphere.

The lower portion of the housing 68 has connected thereto one end of a fuel line 73 which communicates with the lower chamber of the housing below the diaphragm 69 through a restricted orifice 74. The opposite end of the fuel line 73 is connected preferably with the fuel line 33 which, as before stated, is in communication with the escapement burner 27 through the renoid valve is preferably operated with a snap ac-V tion, and for this purpose I may employ the construction fully shown and described in my prior Patent No. 1,875,947,but as the details of construction of this valve per se form no part of the present invention, the valve is illustrated more or less conventionally herein, and reference may be had to my prior patent if a more detailed understanding of the construction and operation of the valve is desired.

In the operation of the device, let it be assumed that the solenoid valve 26 is closed and that valve disk 44 in the thermally actuated valve 40 is in closed position and that gas pressure is present in the main supply -line 16. 'I'his pressure will be present on the lower side of diaphragm 31 of diaphragm valve 30, and an equal pressure will build up in fuel line 36 beyond the orifice 37 and, therefore, on the upper side of diaphragm 31. Due to the'greater area on the upper side of diaphragm 31 subject to the gas pressure, and also due to its own weight, the valve disk 35 will be held seated firmly on the valve seat 34. Under this condition, the lower side of the damper-actuating diaphragm 69 will be at atmospheric pressure as it is in communication with escapement burner 27, through orifices 74 and 29. Therefore, the weight of the moving parts of the damper operating mechanism will have caused the damper 15 to assume the open position, or as near to wide open posiof diaphragm 69.

tion as will be permitted by the adjustment of the nut 71 upon the rod 67. The upper compartment of the main diaphragm valve 17 is also in communication with the escapement burner 27 through orifice 29 and is, therefore, at atmospheric pressure, thus permitting the pressure ofthe gas in main supply line 16 to hold the valve disk 23 away from the seat 22 allowing the gas to flow through outlet pipe 18 and thence to the burner or burners 19.

Now assuming that heating of the water in which thermally responsive tube 51 is immersed causes the tube to expand suflciently to permit spring 45 to unseat valve disk 44 from its seat 43, gas then ows from conduit 46 past valve disk 44 and then through fuel line 48 to escapement burner 27. This gas is small'in amount, being restricted by orifice 37, and there-is a consequent drop in pressure on the upper side of diaphragm 31 of diaphragm valve 30. When this drop in pressure becomes sufhcient in amount, as it does when valve disk 44 has opened a very small amount, the resulting preponderance in pressure on the under side of diaphragm 31 lifts valve disk 35 away from its seat 34, permitting gas to flow through fuel line 33 to the upper side of diaphragm 24 of main diaphragm control valve 17. The escape of gas from fuel line 25 to escapement burner 27 is restricted by oriflce 29, thus causing gas pressure to build up in the upper compartment of main diaphragm valve 17 above the diaphragm 24. When the pressures abve andA below diaphragm 24, are lsubstantially-balanced, the diaphragm will fall, causing valve disk 23 to engage valve seat 22, thereby closing off the flow of gas to the burner or burners 19. At the same time, gas passes from the fuel line 33 through the fuel line 73 past the orifice 74 into the lower compartment of the housing 68 beneath the diaphragm 69. Sufficient pressure is immediately built up to lift diaphragm 69 and thus rotate shaft 58, and damper 15 is moved to closed position. Thus when the main diaphragm valve 17 is causedto close by the heating of the thermally responsive member 51, damper 15 is simultaneously closed, thus preventing air from flowing from the boiler room through the relief opening 13 in the draft hood 11 and thus through flue pipe 12 into the chimney. The action of the diaphragm valve 30 is such as to .cause a sudden admission of pressure -to the upper side of diaphragm 24 of the main diaphragm valve 17 instead of a gradual admission as would be the case if the thermally actuated valve 40 had its outlet connected directly to the upper compartment side of diaphragm 24 of the main diaphragm valve 17.

.Now when the thermally responsive tube 51 of the valve 40 becomes cooler, due to the application of heat to the water in the boiler or air in the furnace having ceased, valve disk 44 gradually seats upon valve seat 43. 'Ihis causesa pressure to build up in fuel line 46 and similarly on the upper side of diaphragm 31 of diaphragm valve 30. When this building up in pressure has proceeded far enough, diaphragm 31 falls by its own weight and valve disk 35 seats on valve seat 34, thus suddenly cutting off the gas pressure in fuel line 33 which is in communication with the upper side of the diaphragm 24 of the main diaphragm valve 17, as well as on the lower side The pressure present in these fuel lines is dissipated through orifice 29 and escapement burner 27, and consequently, the

, pressure having been relieved from the upper the diaphragm 69, it will still be possible, by the opening of the valve 44 in the thermally respon'- sive valve 40, due to heating of the water or air, to build up a pressure in fuel line 73 and thus cause the valve disk 23 to engage its seat 22 and thereby shut off the flow of fuel tothe burner. Orifice 74 is in the nature of a safety feature.

When the thermostat member 76, due to heating of the presmises in which the thermostat is located, makes contact with the hot termi nal 77, the circuit is set up through battery 79 and conductor 80 which causes solenoid valve 26 to open. Gas is thus admitted instantly through Yfuel line 25 tothe upper side of diaphragm 24 of main diaphragm valve 1 7 and to the lower side of diaphragm 69. The action is the same as heretofore described, namely, that diaphragm 24 drops, setting valve disk 23 against valve seat 22 and cutting off the flow of fiuid to the main burner or burners 19 .at the same time causing diaphragm 69 to be raised and, through its link connection with damper 15, causing the latter to be moved to its closed position. Cooling of the premises in which the thermostat 76 is located causes it to make contact with the cold consipated through orifice 29 and escapement burner 27, permitting diaphragm 24 to be raised, thus unseating valve disk 23 from its. seat 22, which permits the fuel to again flow to the main burner. At the same time, the weight of the diaphragm 69 and the link connection with the damper 15 causes the damper 15 to be moved to its open position.

'Ihus it -will be seen that the damper in the flue pipe is caused to move in substantial synchronism with the opening and closing of the main diaphragm valve and that its .movement is quite independent of or is unaffected by variationsin pressure that may exist on' the outlet side of the main diaphragm valve. Likewise, it will be seen that the gradual action of the valve 40 with its thermally controlled mechanism is transformed through the diaphragm valve into a sudden application or relief ef pressure on the upper side of the diaphragm 24 and on the' lower side of the diaphragm 69 of the pressure responsive device which actuates the damper. This is of great advantage in that it causes the diaphragm 24 and its valve disk 23 to seat and unseat suddenly rather than with a fluttering movement as would be the case if the outlet side of the thermostatically controlled valve were connected directly to the upper compartment of the main diaphragm valve 17.

It will be seen also that, although the gas pressure which actuates the diaphragm of the main diaphragm valve 17 is exerted also against another diaphragm, such as the diaphragm 69,

stricted orice 74. Likewise, as has been pointed out, the use of the adjusting nut 71 permits the Wide open position of the damper to be varied, thus permitting control of the effect of chimney draft upon the outlet side of the draft hood, thereby promoting economical operation.

While the diaphragm valve is preferably employed to effect a quick or snap action in the closing and opening of the main diaphragm valve 17, the latter can be made to suitably operate when controlled by a gradually acting valve such as the thermally responsive valve or an equivalent pressure responsive valve.

Under these circumstances the fuel pipe 32 will be connected directly with the inlet side of the valve 40 and the fuel pipe 48 from the outlet side of the valve 40 with fuel pipe 73 so` as to communicate with the under side of the diaphragm 69 and the inlet side of the restricted orifice 29 associated with the escapement burner 27. Such an arrangement therefore eliminates the fuel pipe 36 and its restricted orifice 37, the diaphragm valve 30 and `the fuel pipes 33 and 46 leading therefrom.

With the above arrangement upon the gradual opening of the valve 40 fuel is gradually admitted into the fuel pipe 48 with the result that pressure is gradually built up upon the under side of the diaphragm 69 and upon the upper side of the diaphragm 24 of the main diaphragm valve 17, thus causing the latter to be moved to its closed position as well as causing the damper 15 in the flue pipe 12 to be moved to its closed position. Upon the gradual closing of the valve 40 the flow `of fuel therethrough is cut off with the result that the fuel pressure upon the under side of the diaphragm 69 and upon the upper side of the diaphragm 24 of the main diaphragm valve 17 is dissipated or relieved through the restricted orice 29 in the escapement bumer 27, thus causing the damper to be gradually moved to its open position and the main diaphragm valve 17 to be gradually closed to shut off the flow of fuel to the burner 19.

While I have shown one embodiment of the invention, I do not desire to be confined to the precise details or mechanism shown. For example, instead of the thermally operated valve 40, I may employ a valve which is controlled by the pressure condition in the boiler, and while I have referred to the use of a thermostatic element in the water system of a boiler, a thermostatic element may be used with an air furnace. Furthermore, I may, if desired, modify many other parts, such, for example, as the mechanism for controlling the main gas valve, which may be similar to that disclosed in my Patent No. 1,875,947, for the purpose of causing the flow of gas to be gradually reduced under certain circumstances more fully described in my patent. By such control mechanism there would result a varying gas pressure on the outlet side of the main diaphragm valve, but, as previously pointed out, the actuation of the damper in the iiue pipe is or would be Wholly unaffected by said variation. I therefore aim in my claims to cover all modifications which do not depart from the spirit and scope of the invention as set forth in the appended claims.

Having thus described my invention, I claim:

1. In a heating apparatus, a heating unit, a line for permitting the flow of fuel thereto, a main valve for starting and stopping the flow of fuel, a control mechanism for said valve, a ue pipe having means to permit the passage of air thereinto from outside the unit, and means acting upon the closure of the Amain fuel valve for preventing air from passing from outside said unit into said flue pipe.

2. In a heating apparatus, a heating unit, a line for supplying gas to the heating unit having a main valve, a flue pipe extending from the heating unit and provided with a draft hood and with a damper located beyond the hood, and means for causing the automatic closing of the valve and the damper and for causing the automatic opening of the valve and the damper.

3. In a heating apparatus, a heating unit, a line for supplying gas to the heating unit having a main valve, a flue pipe extending from the heating unit and provided with a draft hood and with a damper located beyond the hood, and means for causing the automatic closing of the valve and the damper and for causing the autovmatic opening of the valve and the damper, the

opening and closing of the two parts occurring substantially simultaneously.

4. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a ue pipe at the upper portion of said unit, means to control the passage of air thereinto from outside said unit, and a fuel pressure responsive device arranged to op'erate said means.

5. In a fuel burning apparatus, a heating unit, a, burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the ow of fuel to said burner, a flue pipe at the upper portion of said unit, means to control the passage of air thereand means for supplying pressure to said pressure responsive device When pressure is applied to the diaphragm of the main valve to close the same.

6. In a gas red heating apparatus, a heating unit, a fuel supply line having a main diaphragm valve, a flue pipe connected with said unit, means to control the passage of air thereinto from out#- side said unit, a pressure responsive' device for actuating the same, a normally closed valve with connections to supply gas to the main diaphragm valveA and to said pressure responsive device, and means for controlling said last mentioned valve whereby both said main diphragm valve and said pressure responsive device are actuated.

7. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a flue pipe at the upper portion of said unit, means in said ue pipe to permit passageof air thereinto from outside said unit, a flue pipe control device, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and operatively connected with said flue pipe control device, a valve connected in said fuel line, and means for actuating said valve whereby upon the opening and closing thereof said main diaphragm valve and said flue pipe control device are caused to be moved to closed and open positions.

8. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line'connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a flue pipe at the upper portion of said unit, means in said flue pipe to permit passage of phragm valve whereby upon the opening and closing thereof said main diaphragm valve and said flue pipe control device are caused to be moved to closed and open positions.

9. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuelsupply line and adapted to control the flow of fuel to said burner, a ue pipe at the upper portion of said unit, means in said flue pipe to permit passage of air thereinto from outside said unit, a flue pipe control device, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and operatively connected with said flue pipe control device, a second diaphragm valve connected in said fuel line, and valve actuated means operatively connected with said second mentioned diaphragm valve for controlling the operation thereof whereby upon the opening and closing of said valve actuating means said main diaphragm valve and said flue pipe control device are caused to be moved to closed and open positions.

10. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a'main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a flue pipe at the upper portion of said unit, means in said ue pipe to permit passage of air thereinto from outside said unit, a ue pipe control device, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and operatively connected .with said flue pipe control device, a valve connected in said fuel line, and thermally or pressure responsive means operatively connected with said valve whereby upon the opening and closing thereof said main diaphragm valve and said flue pipe control device are moved to closed and open positions. l

11. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, al fuel supply line connected to said burner, a main diaphragm valve connected in said fuel line 'and adapted to control the flow of fuel to said burner, a fiue pipe at the upper portion of said unit, means in said flue pipe to permit passage of air thereinto from outside said unit, a ue pipe control device, a fuel line connecting said supply line-with one side of the diaphragm of said main diaphragm valve, a valve connected in said fuel line, and thermally responsive means for controlling the ,operation of said valve whereby upon a variation in temperature from a prede-I termined degree said valve is caused to be opened and closed to thereby cause said main diaphragm valve and said flue pipe control device to be moved to closed and open positions.

12. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel line and adapted `to control the flow of fuel to said burner,

connected in said fuel line, and thermally rev* sponsive means for controlling the operation of said valve actuated by temperature changes in the medium being heated whereby said valve is caused to be opened and closed to thereby cause said main diaphragm valve and said flue pipe control device to be moved to closed and open positions.

13. In a fuel burning apparatus, a heating unit,

a diaphragm for controlling the movement of said flue pipe control device, adjustable means connecting said damper and said diaphragm, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and with said pressure actuated means, fuel relief means connected to said fuel line, a valve connected in said fuel line, and means for actuating said valve whereby upon the opening and closing thereof said main diaphragm valve and said flue pipe control device are moved to closed and open positions.

14. In a fuel burning apparatus, a heating unit, a burner positioned beneath rsaid unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a flue pipe at the upper portion of said unit, means in said fiue pipe to permit passage of air thereinto from outside said unit, a flue pipe control device, a fuel line connecting said supply line with one side`of the diaphragm of said main diaphragm valve and operatively connected with said flue pipe control device, av normally closed diaphragm valve connected in said fuel line, a fuel relief means connected'in said fuel line, said fuel line also having a portion connecting one side of the diaphragm of said second mentioned diaphragm valve with said fuel relief means, a valve connected in said portion of said fuel line, and thermally or pressure responsive means for actuating said valve, whereby upon the opening of said valve said second mentioned diaphragm valve is opened to thereby cause said main diaphragm valve and said flue pipe control device to `be moved to closed positions.

15. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said Afuel supply line and adapted to control the ow of fuel to said burner, a ue pipe at the upper portion of said unit, means in said flue pipe to permit passage of air thereinto from outside said unit, a ue pipe control device, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and operatively connected with said flue pipe control device, al normally closed diaphragm valve connected in said fuel line, an escapement burner connected in said fuel line and having a restricted. orifice therein,

said fuel line also having a portion with a restricted orifice connected to one side of the diaphragm of said second mentioned diaphragm valve and with said escapement burner, a valve connected in vsaid portion of said fuel line, and means for causing the actuation of said valve whereby upon the opening of said valve said second mentioned diaphragm valve is opened to thereby cause said main diaphragm valve and said flue pipe control device to be moved to closed positions.

16. In a fuel burning apparatus, a heating unit, a burner'positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel supply line and adapted to control the flow of fuel to said burner, a ue pipe at the upper portion of said unit, means in said flue pipe to permit passage of air thereinto from outside said unit, a pressure actuated flue pipe control device, a fuel line connecting said supply line with one side of the diaphragm of said main diaphragm valve and with said pressure actuated flue pipe control device through a restricted orifice, a normally closed diaphragm valve connected' in said fuel line, fuel relief means connected in said fuel line, said fuel line also having a portion connected to one side of the diaphragm of said second mentioned diaphragm valve and with said fuel relief means, a valve connected in said portion of said fuel line, and thermally or pressure responsive means for actuating said valve whereby upon the opening of said valve said second mentioned diaphragm valve is opened to thereby cause said main diaphragm valve and said pressure actuated flue pipe control device to be moved to closed positions.

17. In a fuel burning apparatus, a heating unit, a burner positioned beneath said unit, a fuel supply line connected to said burner, a main diaphragm valve connected in said fuel line and adapted to control the flow of fuel to said burner, a ue pipe at the upper portion of said unit, means in said flue pipe to permit passage of air thereinto from outside said unit, a pressure actuated inga portion with a restricted orice connected to one side of the diaphragm of said second mentioned diaphragm valve and with said escapement burner, a valve connected in said portion of said fuel line, and thermally or pressure responsive means actuated by temperature changes within the medium being heated for controlling the operation of said valve whereby upon the opening of said valve said second mentioned diaphragm valve is opened to thereby cause said main diaphragm valve and said flue pipe control device to be moved to closed positions.

18. In a heating apparatus, a heating unit having a flue pipe provided with a draft hood and a damper beyond the draft hood, a fuel line for supplying fuel to the heating unit, a main valve therefor with automatic control, and means for closing the damper when said valve is closed.

19. In a heating apparatus, a heating unit having a flue pipe provided with a draft hood and a damper beyond the draft hood, a fuel line for supplying fuel to the heating unit, a main valve therefor with automatic control, and means for causv ing the opening and closing of the damper when said valve is opened and closed respectively.

20. In a heating apparatus, a heating unit having a flue pipe provided with a draft hood and a damper beyond the draft hood, a fuel line for supplying fuel to the heating unit, a main valve therefor, means for automatically causing the closing and opening of said valve, and means for causing the damper to be opened and closed substantially coincidentally with the opening and closing of said valve.

WILLET E. STARK.

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